Rising BMI and fat mass linked to ultra-processed food consumption in young Chilean children

A recent study published in BMC Medicine has illuminated the significant relationship between the consumption of ultra-processed foods (UPFs), rising obesity rates, and certain metabolic indicators among preschool-aged children in Chile. The findings underscore the potential long-term health risks associated with diets high in UPFs, particularly in young children, a demographic increasingly vulnerable to the adverse effects of poor nutrition.

Study Overview

The study was conducted as part of the Food and Environment Chilean Cohort (FECHIC) study, a prospective cohort investigation designed to explore the impact of dietary habits on health outcomes in Chilean children. The researchers focused on the influence of UPF consumption on obesity and metabolic outcomes over a two-year period, with initial data collection beginning in 2016.

Participant Selection and Data Collection

The study analysed dietary data from 962 children, all of whom were around four years old at the start of the research. Dietary intake information was collected using the United States Department of Agriculture’s (USDA) multiple-pass technique, a method known for its accuracy in capturing 24-hour dietary recalls. Mothers served as the primary respondents, providing detailed accounts of their children’s food intake during structured in-person interviews. Where necessary, the children themselves contributed additional details about their eating habits, especially for meals consumed outside the home, such as during school hours.

In order to maintain the integrity of the study, records indicating extreme levels of UPF consumption were excluded. The researchers utilised the NOVA classification system to categorise all foods consumed by the participants. This system divides foods into four categories: natural and minimally processed foods, processed culinary ingredients, processed foods, and ultra-processed foods. To estimate the children’s UPF consumption both in terms of grams and calories, the Multiple Source Method (MSM) was employed.

Assessment of Adiposity and Metabolic Indicators

Two years after the initial data collection, when the children had reached the age of six, the research team measured various indicators of adiposity and metabolism. Adiposity indicators included waist circumference, body fat mass (both as a percentage and in kilograms), and body mass index (BMI) z-scores. The metabolic indicators assessed were fasting blood glucose levels, insulin levels, the homeostatic model assessment for insulin resistance (HOMA-IR), low-density lipoprotein cholesterol (LDL-c), high-density lipoprotein cholesterol (HDL-c), triglycerides, and total cholesterol.

To evaluate the children’s energy requirements, the Dietary Reference Intake (DRI) equation was applied. The relationship between UPF intake and the various health outcomes was analysed using linear regression models, which were adjusted for covariates such as age, sex, baseline BMI z-scores, screen time, and maternal factors including BMI, age, education, employment status, and socioeconomic status.

Results and Analysis

At the beginning of the FECHIC study, the average age of the children was five years, with a slight female majority (52%). The average BMI z-score was recorded at 1.0, indicating a tendency towards overweight. The mothers were, on average, 31 years old, with 55% having attained a medium level of education.

By the end of the two-year study period, the average fat mass of the children had risen to 24%, and the average fasting glucose level was measured at 82 mg/dL. Notably, UPFs accounted for 48% of the children’s total caloric intake at four years of age, and 39% of their total food intake by weight. Despite UPFs contributing the majority of calories, minimally processed foods still constituted the largest portion by weight (57%).

The adjusted regression models revealed significant positive associations between UPF consumption and several key indicators of obesity, including BMI, waist circumference, fat mass in kilograms, and percentage fat mass. However, the study did not find a direct relationship between UPF intake and the metabolic markers assessed.

Sensitivity analyses, which included models without the use of stabilised inverse probability of censoring weights and considered UPF intake in quartiles, produced consistent results, further reinforcing the study’s findings.

Discussion

The study’s results suggest that the proportional contribution of UPFs to the diet is more impactful than the total quantity consumed. This observation aligns with broader research indicating that health improvements often follow a shift away from diets dominated by ultra-processed foods.

UPFs are typically characterised by a poor nutritional profile, with high levels of added sugars and saturated fats, and low concentrations of essential vitamins and minerals. The production processes involved in creating UPFs often use refined ingredients that not only reduce satiety but also increase glycaemic response, leading to a higher propensity for overeating. Additionally, UPFs are energy-dense but low in water content, allowing for rapid consumption of both volume and calories, which further promotes excessive intake. The low protein density in these foods may also contribute to an overconsumption of other, potentially unhealthy, foods.

There is also concern that the widespread consumption of UPFs increases exposure to rare or unnatural food additives, which could pose additional, as yet unquantified, health risks.

Conclusion and Recommendations

The findings from this study indicate a clear link between UPF consumption and rising obesity rates among Chilean preschoolers, though no significant connection to metabolic consequences was observed within the two-year period. Longer follow-up studies are necessary to fully understand the long-term risks associated with UPF consumption in young children.

In light of these findings, health authorities and policymakers are urged to strengthen global initiatives aimed at creating environments that encourage diets rich in minimally processed foods. There is a pressing need to restrict children’s access to UPFs, which are increasingly prevalent in modern diets, to curb the growing trend of childhood obesity and its associated health risks.